1. Field of the Invention
The present invention is directed to an improved dampening device in a device for supplying ink by a common distributor unit to a plurality of printing ink jets provided in a printer head of a mosaic printer unit.
2. Prior Art
German Offenlegungsschrift No. 2,262,106, U.S. Pat. No. 3,708,798, discloses a tubular distributor arrangement which communicates with each printing ink jet of a piezoelectric operated printer head. To dampen incompressible hydraulic pressure waves or pressure fluctuations in the ink supply, the distributor arrangement is provided with a volume of air in the form of an included bubble of air which will be compressed and expanded in response to hydraulic pressure fluctuations in the ink supply.
This type of dampening arrangement which utilizes an included bubble of air had several drawbacks. For example, the volume of the air bubble can vary depending on the nature of the ink and the thermal conditions in the distributor arrangement. In addition, over a long period of time, the volume and the elastic characteristics of the air bubble will change due to the air being absorbed in the printing liquid. Due to the physical separation of the ink distributor arrangement from the printer head which is moving along a data carrier, additional pressure oscillations or fluctuations will occur. It is extremely difficult to compensate for these oscillations or fluctuations by using the known dampening device which comprises a bubble of air.